Repeat units are the smallest segments of a polymer that can undergo polymerization independently. These molecules contain two distinct functional groups capable of reacting with each other. When two monomer units are present in equal concentrations, they theoretically react in a 1:1 ratio to form an equivalent number of repeat units. However, if the concentration of one monomer is lower than the other, the number of repeat units formed will be limited by the concentration of the lesser monomer. Once the lower-concentration monomer is fully consumed, any excess of the other monomer will remain unreacted and will not contribute to the polymer structure. Adjusting the relative concentrations of the monomers is a common method for controlling the molecular weight of the resulting polymer.

None of the polymer is 100% crystalline. so dH for 100% crystalline polymer is a theoretical value which is taken from literature.

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Thanks for your comment. Regarding backpressure, it is a very important process parameter since it helps to push material forward leading to better compaction of the melt and also removes voids. Higher backpressure also helps to achieve better shear mixing. This all help to achieve a high quality product. But excess backpressure can also lead to over heating and chain breakage leading to poor mechanical property or defects. So an optimum value of backpressure should be used.

@@PolymerWorld Really appreciated of your detailed explanation. Thanks again.

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If the chain side chain contains big bulky group like phenyl group, side groups or branching restricts the chain movement which leads to higher Tg. If the side group is small like methyl or ethyl side group, chain can easily move compared to bulky side group. In this case Tg will be low. I hope it helps.

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Thanks for watching our videos. The ratio of PVC powder to plasticizer for soft vinyl toys is generally in the range of 100:40 to 100:80 (w/w), depending on the specific requirements for softness and flexibility.

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Both types of extruders have their strengths and limitations. Twin screw extruder is generally preferred for color masterbatch production due to its excellent mixing efficiency as it gives better dispersion compared to single screw extruder.

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First try to understand the fundamentals of DMA then apply your knowledge in analyzing some of the DMA scans. This will certainly help.

@@PolymerWorld how to remember study..?

This presentation is compilation of different research articles. But you can consult book Thermal analysis of polymers: fundamentals and applications by Joseph D Menczel. This book can be helpful.

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It was a semicrystalline PLA.

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